Pressure combustion boiler



March 28, 1939. B HQFFMANN 2,152,479

PRESSURE COMBUSTION BOIIJER Filed Feb. 15, 195'? Fig.1.

Inventor: Bruno Hoffmann,

by His Attorneg.

Patented Mar. 1939 mmssnnn COMBUSTION BOILER Bruno Hofl'mann, Berlin-Spandau, Germany; assignor to General Electric Company, a corporation of New York Application February 15, 1937, Serial No. 125,901

' In Germany February 28, 1936 3 Claims.

The present invention relates to pressure combustion boilers to which air for maintaining combustion is supplied under pressure by means of a blower or centrifugal pump driven by a gas 5 turbine receiving combustion gases discharged from the boiler. In certain cases, for instance where this type of boiler is used for operating aircraft, it .has been found difl'icult to form foundations with the rigidity and of the size required for quiet operation of the boiler and the auxiliaries connected thereto and forming parts thereof.

The object of the present invention is to provide an improved construction and arrangement 15 of pressure combustion boilers whereby the afore-' mentioned difflculties are overcome. This is accomplished in accordance with my invention by supporting the auxiliaries including the gas turbine, the blower, fuel pump, starting motor, as

20 well as the preheater and the fuel tank on the casing of the boiler; in other words, by uniting the boiler with the auxiliaries to form a single, unitary, compact block. This block is preferably provided with two supporting elements near its 25 center line of gravity. In this manner an entirely rigid system is produced which makes it possible to support the entire system on comparatively small supporting surfaces. Such arrangement in addition has other advantages. 30 The necessary pipe connections, for instance the overflow pipe from the boiler to the gas turbine, become very short and wide so that heat stresses and pressure losses are reduced to a minimum. This is especially possible when the air preheater 35 is arranged to form a ring surrounding the boiler casing.

For a better understanding of what I believe to be novel and my invention, attention is directed .o the following description and the claims appended hereto in connection with the accompanying drawing.

In the drawing, Fig. 1 represents a diagrammatic view of a section through a boiler arrangement embodying my invention, and Fig. 2 illus- 45 trates a top view partly in section of Fig. 1.

. More specifically, the arrangement shown in the drawing comprises a boiler proper having an inner casing l0 surrounded by an outer casing ll'.'

These casings form a chamber l2 between them go for preheating the combustion air. A heating element I3 is disposed in the combustion chamber formed within the-inner casing III. This heating element has an inlet connected to the discharge of a circulating pump H, which latter u is connected to an economizer or preheater I5 the burner I8 by means including a blower or centrifugal pump or compressor 23 having an impeller chamber with an impeller 24. During operation, air is forced through an inlet 25 and discharged from a scroll 26 of the centrifugal pump 23 through a conduit 21 to an air preheater. The centrifugal pump 23 is driven in known manner by an exhaust gas turbine. 28 which receives combustion gases exhausted from the combustion chamber of the boiler. The

aforementioned fuel pump 20 is connected to the shaft of the centrifugal-pump 23 by a gearing 23 so that during normal operation the fuel pump 20 is also driven by the exhaust gas turbine 28. During starting operation the fuel pump and the centrifugal blower are operated by means of an auxiliary motor, in the present instance indicated as a small combustion engine 30, connected to the gearing 29 by means of a gear 3| and a clutch 30 32. The air preheater for preheating the air discharged from the centrifugal blower through the conduit 21 comprises in accordance with my invention a plurality of rows of heating tubes, 33 concentrically arranged about the upper portion 35 of the inner casing I0 and connected at their upper ends to a header 34 and at their lower ends to the aforementioned'air preheating cham- I ber l2. During operation, the air discharged from the centrifugal blower through the conduit 40 21 is conducted to the upper header 3!, whence it flows downwardly through the heating tubes 33 into the chamber l2 and the burner Ill. The

preheating of the air conducted through the heating tubes 33 is effected by the gases discharged from the exhaust gas turbine 23. These gases also serve to preheat the fuel. Thisis accomplished by the provision of a plurality of heating tubes 35 in the fuel tank I9. These heating tubes receive the gases discharged from go the air preheater. In this manner both the available kinetic energy and the heat energy of the combustion gases exhausted from the boiler are utilized and regained.

In accordance with my invention all of the I5 I auxiliary motor are secured to the left-hand side of the outer casing I l by means including a bracket 31. The liquid preheater I5 is also secured to the left-hand side of the outer casing I l by means including another bracket 38. In this manner, the weight of the auxiliaries and the fuel tank is balanced with regard to the boiler proper. The whole structure thus forms a single I block which is supported on struts 39 and 40 of an aircraft. The support is provided near the center line of gravity of the block.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A portable pressure combustion boiler arrangement including the combination of a boiler proper having a casing and a heating element therein, auxiliaries comprising a blower, a fuel pump and a starting motor together with a tank for fuel, said auxiliaries forming two groups completely supported ,on and securedto opposite portions of the boiler casing, and means including passages formed in the tank for receiving combustion gases to preheat the fuel.

2. A pressure combustion boiler including the combination of a boiler proper having an inner and an outer casing forming a chamber for preheating combustion air, a burner, means including a gas turbine receiving combustion gases discharged from the boiler and a blower driven by the turbine for 'forcing air through said 7 ing a heating element and a burner, an air preheater surrounding the casing, means including a gas turbine arranged to receive the combustion gases discharged from the boiler and a centrifugal pump driven from the gas turbine for forcing air through the preheating chamber into the burner, a tank for fuel including a plurality of heating tubes receiving gases discharged from the preheating chamber to preheat fuel in the tank and a fuel pump for forcing fuel from the tank into the burner, means including a bracket secured to one side of the casing to support the gas turbine, the centrifugal blower and the fuel pump, and means including another bracket secured to the opposite side of the casing for supporting the tank and to balance the weight of said gas turbine, centrifugal blower and fuel pump on the opposite side of the casing, the brackets form-- ing supporting surfaces for the entire arrangement near the center line of gravity thereof.

BRUNO HOFFMANN. 

